Antinfective free intramammary veterinary composition

ABSTRACT

An antiinfective-free formulation for prophylactic traetment of mastitis in dry cows comprises a seal formulation having approximately 65% by weight of bismuth sub-nitrate in a gel based on aluminium stearate. The seal formulation is prepared by adding the bismuth sub-nitrate to the gel base in at least two separate stages.

INTRODUCTION

[0001] The invention relates to a veterinary composition, particularlyfor the prophylactic treatment of mastitis in cows.

[0002] Bacterial infection via the teats of a cow is the most commoncause of mastitis.

[0003] It is know to treat teats of a cow with a long acting antibioticin a slow release form with effective cover only being provided whilstminimum inhibitory concentration (MIC) levels of the antibiotic aremaintained. This period of cover can vary from 4 to 10 weeks.

[0004] It is also known to infuse a cloxacillin-based antibiotic intothe udder following the last lactation and before the cow is dried off,immediately followed by a seal formation to seal the teat canal.

[0005] The invention is directed towards providing an improvedveterinary composition, particularly for the prophylactic treatment ofmastitis in dry cows.

STATEMENTS OF INVENTION

[0006] We have found that if a physical barrier is provided within theteat canal and/or the lower teat sinus during the dry period without theuse of antibiotics, the incidence of mammary disorders is substantiallyreduced. This is very surprising as all conventional treatments involvethe use of antibiotics. Because no antibiotics are required verysubstantial advantages result, without any significant reduction ineffectiveness.

[0007] According to the invention there is provided anantiinfective-free formulation for prophylaxis of intramammary infectioncomprising a seal formulation to provide a physical barrier in the teatcanal.

[0008] This non-antibiotic approach to preventing new dry periodinfection in dairy cows has major potential for the dairy industry as itresults in the reduction of the incidence of antibiotic contamination inearly season milk production. Thus the invention provides a qualityimprovement to dairy production and will facilitate farmers, meetingconsumer preferences for reducing the level of antibiotics used in foodproduction.

[0009] According to another aspect the invention provides anantiinfective-free method of prophylactic treatment of mammary disordersin non-human animals during an animal's dry period by sealing the teatcanal with a seal formulation to provide a physical barrier in the teatcanal.

[0010] The invention also provides a prophylactic method of controllingthe infection of the mammary gland by a mastitis-causing organism bysealing the gland with a seal formulation to provide a physical barrierin the teat canal.

[0011] In a particularly preferred embodiment of the invention the sealformulation comprises a non-toxic heavy metal salt in a gel base.Preferably, the heavy metal salt is present in an amount of between 50%and 75% by weight, most preferably approximately 65% by weight. We havefound that these are the optimum levels of heavy metal salt to achievean effective seal.

[0012] In a preferred embodiment of the invention the heavy metal saltis bismuth subnitrate. This is a particularly useful non-toxic heavymetal salt.

[0013] In one embodiment of the invention the base is a gel based onaluminium stearate. Preferably, in this case, the gel includes a vehiclesuch as liquid paraffin. This formulation has effective processing anduse properties.

[0014] In another embodiment of the invention the gel comprises apolyethylene gel. The gel may be based on low density polyethylene or onhigh density polyethylene.

[0015] The invention also provides a veterinary composition for use inthe prophylactic treatment of mammary disorders in non-human animalsduring an animal's dry period.

[0016] According to a further aspect the invention provides a processfor preparing a seal formulation comprising the steps of adding anon-toxic heavy metal salt to a gel base in at least two separatestages. This process is particularly effective for producing thepreferred seal formulation of the invention.

[0017] Preferably, a first portion of heavy metal salt is added to a gelbase in a first stage and a second portion of the heavy metal salt isadded to the gel base containing the first portion of the heavy metalsalt.

[0018] In this case preferably the weight ratio of the second portion ofthe heavy metal salt to the first portion of the heavy metal salt is atleast 1:1, most preferably approximately 2:1.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The invention will be more clearly understood from the followingdescription thereof given by way of example only.

EXAMPLE 1

[0020] Raw Materials: Liquid Paraffin B.P. 434.8 Kg Alugel 30 DF(Sterile) 69.2 Kg Bismuth Sub-Nitrate 936.0 Kg B.P.C. (Sterile)

[0021] To prepare a batch of seal formulation the liquid paraffin isfirst delivered into a Skerman 800L kettle. The mixer is run at 20 RPM.The Alugel 30 DF (aluminium stearate) is then added through the transferport. The mixer is turned off between additions of the Alugel powder.The steam line is opened and the temperature is allowed to rise to 160to 165° C. This temperature is held for approximately 2 hours tosterilise the mixture. At the end of the sterilising cycle, thecondensate valve is opened and blown down. Cooling water is then allowedinto the jacket to cool the contents to less than 40° C. The base thusformed is then checked for quality. If necessary, the batch base may behomogenised for 10 minutes using a Silverson Homogeniser.

[0022] The charge port is then opened and 296 kg of the bismuthsub-nitrate is added in 10 kg lots. The contents are mixed for oneminute at 20 RPM between additions of each 10 kg of bismuth sub-nitrate.Mixing is continued for approximately 1 hour at 45 RPM.

[0023] The remaining 640 Kg of bismuth sub-nitrate is then added in 10Kg lots as above and mixing is continued for 1 hour following the finaladditions.

[0024] We have found that the addition of the bismuth sub-nitrate in twoseparate portions is important in producing a seal which can beprocessed and used effectively.

[0025] If necessary, the mixer is homogenised for 15 minutes using aSilverson Homogeniser.

[0026] The product is then transferred to a Colibri filling machine forfilling into injector tubes.

EXAMPLE 2

[0027] 5 Cows were infused in all four quarters at drying off with theseal formulation prepared as described in Example 1. These cows hadpreviously been determined as uninfected in all four quarters.

[0028] Commencing at the first milking after calving, these cows weremilked and the composite milk sample collected for analysis. Thisprocess was repeated for the first 10 milkings after calving. Milksamples were also collected in the same manner from 5 untreated cows.

[0029] To simulate the milk handling process within the milking system,these milk samples were passed through a fibre filter material used inmilking machine filters. The milk samples were then analysed by massspectrometry for bismuth concentration.

[0030] The average bismuth level in milk drawn at first milking was 3.3ppm declining to 0.39 ppm at milking No. 10. The maximum level recordedfor any individual cow was 8 ppm at first milking. For untreated cowsthe levels fluctuated in the range 0.001 to 0.03 ppm.

[0031] The seal formulation described in Example 1 was administered atdrying off and has been shown to reduce the incidence of new infectionin the dry cow period and in the period around calving. The reductionappears to be comparable with that achieved by prophylactic antibiotictreatment. Thus, the seal of the invention very surprisingly offers anon-antibiotic approach to dry cow period prophylaxis.

EXAMPLE 3

[0032] Evaluation of seal of Example 1.

[0033] 4 Mastitis-free cows selected at drying off.

[0034] 2 Teats in each cow infused at drying-off with seal and remainingteats untreated (day 0).

[0035] 8 Teats sealed and 8 teats untreated (controls).

[0036] 3 Days later (day 3) all teats were inoculated into the teatcanal (depth of 4 mm; using 22 cfu of Streptococcus dysgalactiae code Mand an inoculum volume of 0.1 ml).

[0037] New infections resulting from use of the inoculum occurred infive (5) of the untreated quarters in the period day 3 to day 13.

[0038] New infections resulting from use of the inoculum occurred in two(2) of the treated quarters in the period day 3 to day 13.

[0039] Resulting new infections were monitored daily for 10 consecutivedays after inoculation (to day 13).

[0040] Samples of secretion were collected in an aseptic manner fromquarters showing signs of clinical mastitis prior to treatment withantibiotics.

[0041] All quarters in all 4 cows were sampled in an aseptic manner onday 13 (the last day of the trial)—these samples were used to:

[0042] (1) check the amount of seal remaining in teats

[0043] (2) monitor the level of Str. dysgalactiae surviving in the teatsafter 10 days

[0044] Clinical Infection Results Inoculation CFU/ml Depth Control Seal22 4 mm 5^(a)/8^(b) 2^(a)/8^(b) 63% 25%

EXAMPLE 4

[0045] Evaluation of seal of Example 1.

[0046] 17 Mastitis-free cows* selected at drying off.

[0047] 2 Teats in each cow infused at drying-off with seal and remainingteats untreated (day 0).

[0048] 32 Teats sealed and 32 teats untreated (controls).

[0049] 3 Days later (day 3) all teats were inoculated into the teatcanal (depth of 17 mm; using 1,190 cfu of Streptococcus dysgalactiaecode M and an inoculum volume of 0.1 ml).

[0050] New infections resulting from use of the inoculum occurred intwenty (20) of the untreated quarters in the period day 3 to day 13.

[0051] New infections resulting from use of the inoculum occurred ineight (8) of the treated quarters in the period day 3 to day 13.

[0052] Resulting new infections were monitored daily for 10 consecutivedays after inoculation (to day 13).

[0053] Samples of secretion were collected in an aseptic manner fromquarters showing signs of clinical mastitis prior to treatment withantibiotics.

[0054] All quarters in all 17 cows were sampled in an aseptic manner onday 13 (the last day of the trial)—these samples were used to:

[0055] (1) check the amount of seal remaining in teats

[0056] (2) monitor the level of Str. dysgalactiae surviving in the teatsafter 10 days

[0057] Clinical Infection Results Inoculation CFU/ml Depth Control Seal1,190 17 mm 20^(a)/32^(b) 8^(a)/32^(b) 63% 25%

EXAMPLE 5

[0058] A total of 528 cows in three commercial herds were used. Eachherd had a general history of dry period mastitis. The breed of theherds was predominately Fresian or Fresian crosses.

[0059] Cows with at least three uninfected quarters, immediately priorto drying off, were identified within the three herds. All individualquarters were assumed to be independent units. The treatments used wereas follows.

[0060] 1. Negative Control-Untreated, no infusions at drying off, butteat ends were sanitised with alcohol soaked cotton wool swabs.

[0061] 2. Positive Control-treated with 250 mg cephalonium in along-acting base, infused at drying off. This product is known asCEPRAVIN DRYCOW. Cepravin is a trademark of Mallinckrodt Veterinary.

[0062] 3. Antibiotic with Seal-Cloxacillin benzathine 600 mg in a 4 gunit dose infused at drying off and followed immediately by an infusionof 4 g of a blend of bismuth sub-nitrate (66%) in liquid paraffin with8.5% Alugel 30DF.

[0063] 4. Seal—Bismuth sub-nitrate 66% w/w in liquid paraffin with 8.5alugel 30DF in a unit dose of 4 g infused at drying off.

[0064] These treatments were randomised among the 528 cows determined tohave three of four uninfected quarters at drying off. The treatmentswere randomised between quarters to achieve as far as possible the samenumber of quarters per treatment, left and right, front and back.

[0065] Bacteriological results for individual quarters at drying off andat calving were compared to calculate the incidence of new intramammaryinfections (IMI). Chi-square testing was used to compare the incidenceof the new infection between quarters, treatments and controls.

[0066] The results of the treatments are summarised in Table 1.

[0067] This experiment has demonstrated that the antinfective-free sealformulation of the invention administered at drying off is verysurprisingly equivalent in terms of prophylactic efficacy, to a longacting dry cow antibiotic. All three treatments reduced new IMI duringthe dry period by approximately 85%. Surprisingly, there was nosignificant difference between the antibiotic based treatments and theantibiotic-free treatment of the invention. Thus, this study has shownthat by physically sealing the teat canal with a seal which has nobacteriostatic or bacterial action, the dry period IMI may,surprisingly, be controlled. The invention has the potential thereforeof achieving dry period prophylaxis on a wide scale, at a lower unitcost, and with no risk of antibiotic residues after calving.

[0068] The invention is not limited to the embodiments hereinbeforedescribed which may be varied in detail. TABLE 1 New intramammaryinfections (IMI) identified during the study, grouped by period and byherd. (Within a row, values with differing superscripts aresignificantly different) Number of new IMI (quarters) 1. Negativecontrols 2. Positive controls 3. Antibiotic + Seal 4. Seal Herd ID 1 2 31 2 3 1 2 3 1 2 3 Total no quarters 249 141 138 249 141 138 249 141 139249 141 138 DRY PERIOD Clinical IMI 10 6 2 0 1 1 1 1 0 1 0 0 CALVING IMIStrep. Spp. 25 21 4 0 4 1 2 1 1 2 2 0 S. aureus 1 2 0 0 0 0 0 0 0 0 1 0Coag. Neg. staph. 2 0 4 0 0 1 1 0 1 4 0 2 Coliforms 1 2 1 1 2 1 1 0 0 01 0 Other organisms 0 2 0 1 1 0 0 1 0 0 0 0 Clinical, no growth 1 1 0 00 0 0 0 0 0 0 0 Total calving IMI 30 28 9 2 7 3 4 2 2 6 4 2 Total IMI 4034 11 2 8 4 5 3 2 7 4 2 Overal IMI rate (%) 16.1 24.1 8.0 0.8 5.7 2.92.0 2.1 1.4 2.8 2.8 1.4 Toatl IMI across herds & 68^(a)  7^(b)  6^(b) 5^(b) periods Strep. Spp. IMI Other paths IMI 17^(c)  7^(d)  4^(d) 6^(d) All paths IMI 85^(f) 14^(g) 10^(g) 13^(g) Total quarters 528 528528 528 Overall new IMI Rate 16.1% 2.7% 2.5% 1.9%

1. An antiinfective-free formulation for prophylaxis of intramammaryinfection comprising a seal formulation to provide an antiinfective-freephysical barrier in the teat canal.
 2. A formulation as claimed in claim1 wherein the seal formulation comprises a non-toxic heavy metal salt ina gel base.
 3. A formulation as claimed in claim 2 wherein the sealformulation contains at least 40% by weight of the heavy metal salt. 4.A formulation as claimed in claim 3 wherein the seal formulationcontains from 50% to 75% by weight of the heavy metal salt.
 5. Aformulation as claimed in claim 4 wherein the seal formulation containsapproximately 65% by weight of the heavy metal salt.
 6. A formulation asclaimed in any of claims 2 to 5 wherein the salt is bismuth sub-nitrate.7. A formulation as claimed in any of claims 1 to 6 wherein the base isa gel based on aluminium stearate.
 8. A formulation as claimed in any ofclaims 1 to 7 wherein the base includes liquid paraffin as a vehicle. 9.An antiinfective-free formulation substantially as hereinbeforedescribed with reference to the Examples.
 10. An antiinfective-freemethod of prophylactic treatment of mammary disorders in non-humananimals during an animal's dry period by sealing the teat canal with aseal formulation to provide a physical barrier in the teat canal.
 11. Aprophylactic method of controlling infection of the mammary gland by amastitis-causing organism comprising sealing the gland with a sealformulation to provide a physical barrier in the teat canal.
 12. Amethod as claimed in claim 10 or 11 wherein the seal formulationcomprises a non-toxic heavy metal salt in a gel base.
 13. A method asclaimed in any of claims 10 to 12 wherein the seal formulation containsat least 40% by weight of the heavy metal salt.
 14. A method as claimedin claim 13 wherein the seal formulation contains from 50% to 75% byweight of the heavy metal salt.
 15. A method as claimed in claim 14wherein the seal formulation contains approximately 65% by weight of theheavy metal salt.
 16. A method as claimed in any of claims 10 to 15wherein the salt is bismuth sub-nitrate.
 17. A method as claimed in anyof claims 10 to 16 wherein the base is a gel based on aluminiumstearate.
 18. A method as claimed in any of claims 10 to 17 wherein thebase includes liquid paraffin as a vehicle.
 19. An antiinfective-freemethod of prophylactic treatment of mammary disorders substantially ashereinbefore described with reference to the Examples.
 20. A process forpreparing a seal formulation comprising the steps of adding a non-toxicheavy metal salt to a gel base in at least two separate stages.
 21. Aprocess as claimed in claim 19 wherein a first portion of heavy metalsalt is added to a gel base in a first stage and a second portion of theheavy metal salt is added to a gel base containing the first portion ofthe heavy metal salt.
 22. A process as claimed in claim 21 wherein theweight ratio of the second portion of the heavy metal salt to the firstportion of the heavy metal salt is at least 1:1.
 23. A process asclaimed in claim 22 wherein the weight ratio is approximately 2:1.
 24. Aprocess as claimed in any of claims 20 to 23 wherein the sealformulation contains at least 40% by weight of the heavy metal salt. 25.A process as claimed in claim 24 wherein the seal formulation containsfrom 50% to 75% by weight of the heavy metal salt.
 26. A process asclaimed in any of claims 20 to 25 wherein the seal formulation containsapproximately 65% by weight of the heavy metal salt.
 27. A process asclaimed in any of claims 20 to 26 wherein the salt is bismuthsub-nitrate.
 28. A process as claimed in any of claims 20 to 27 whereinthe base is a gel based on aluminium stearate.
 29. A process as claimedin any of claims 20 to 28 wherein the gel contains liquid paraffin as avehicle.
 30. A process substantially as hereinbefore described withreference to the Examples.
 31. A seal formulation whenever prepared by aprocess as claimed in any of claims 20 to 30.